1. Field of the Invention
The present invention relates to a rotating electric machine on which a power element unit making an inverter control is mounted and, more particularly, to a power inverter type an electric rotating machine for vehicles used in, e.g., motor generators, and power steering motors.
2. Description of the Related Art
Conventionally, a power element unit for making an inverter control of a rotating electric machine, for example, as disclosed in the Japanese Patent Publication (unexamined) No. 274992/2004 (pages 17 to 19, FIGS. 1 to 5), is provided with an inverter module that is formed of a plurality of switching elements (power elements such as power transistors, MOSFET, or IGBT) and diodes connected in parallel to each of the switching elements.
In the inverter module, letting the switching element and diode forming an upper arm and the switching element and diode forming a lower arm that are connected in series one set, these three sets are connected in parallel.
An armature winding is in Y-connection. Ends of each phase of the Y-connection are electrically connected to an intermediate point between the switching elements of the upper arm and the switching elements of the lower arm that are connected in series forming one set via an AC wiring corresponding to each of the phases.
Furthermore, as to terminals of a battery, a positive electrode terminal is electrically connected to the positive electrode side of the inverter module, and a negative electrode terminal is electrically connected to the negative electrode side of the inverter module, respectively via a DC wiring.
In the inverter module, the switching operation of each of the switching elements is controlled by commands from a control circuit. Further, the control circuit controls a field current control circuit to adjust a field current to carry through the field winding of the rotor.
Since a large power loss occurs at the time of switching and conduction of the switching elements in the inverter module in driving the mentioned conventional rotating electric machine, it is a particularly important problem to be solved that each of the switching elements forming an inverter module is cooled.
For example, in the cooling system disclosed in the Japanese Patent Publication (unexamined) No. 274992/2004, a power element unit containing an inverter module is located in a circumferential direction on a heat sink at one end in an axial direction of the rotating electric machine, a cooling air is made to flow in flow paths of cooling fins one after another along the cooling fins provided with the flow paths in the radial direction, thereby cooling the heat sinks.
Since the power element unit containing an inverter module according to the mentioned prior art is located in the circumferential direction on the heat sink at one end in the axial direction of the rotating electric machine, a cooling air is made to flow in flow paths of cooling fins one after another along the cooling fins provided with the flow paths in the radial direction, thereby cooling the heat sinks, a problem exists in that a cooling air having been warmed flows into the next cooling fin, eventually resulting in lower cooling performance.